feat(slot): BAT-028 M2/M3 — universe reconcile + 자산 중심 admission (dcy-020/REQ-058·059)

config 게이트 이중 경로(max_active_slots 설정 시 자산 중심, 미설정 시 legacy pool).
운영 데몬은 cutover(BAT-δ) 전까지 pool 무중단.

- repository: find_slot_by_portfolio·count_active(holding+pending_buy+pending_sell)·
  reconcile_universe(생성 멱등/soft-retire/tombstone, allow_retire 가드) — protocol+in_memory+PG
  (PG: ON CONFLICT (instance_key, portfolio_id) WHERE portfolio_id IS NOT NULL)
- snapshot_scheduler: run_once swap 직후 _reconcile_slots(빈 universe skip, ≥50%↓ retire 보류)
- intents: _admit_buy 모드 분기 + _admit_buy_asset_centric(활성화/already_active/
  capacity_full/unknown_portfolio/over-cap, 인스턴스 lock)
- daemon: instance_key·max_active_slots·reconcile_enabled·trading_date_fn 배선
- 신규 테스트: test_universe_reconcile(6), test_asset_centric_admission(6), PG reconcile(1)

검증: 단위 387 passed / 35 skipped, PG-gated 17 passed, ruff clean. legacy 무파손.
REQ-058/059/060 은 Approved 유지(자산 중심 경로 도입 검증; default 전환·cutover 는 BAT-δ).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

trex_core/application/snapshot_scheduler.py

@@ -37,6 +37,10 @@ class SnapshotScheduler:
         broker: BrokerPort,
         schedule_kst: time = time(hour=7, minute=30),
         clock: Optional[Callable[[], datetime]] = None,
+        slot_repo=None,
+        instance_key: str = "default",
+        reconcile_enabled: bool = False,
+        trading_date_fn: Optional[Callable[[], object]] = None,
     ) -> None:
         self._read = read_port
         self._store = store
@@ -45,6 +49,13 @@ class SnapshotScheduler:
         self._clock = clock or (lambda: datetime.now(tz=timezone.utc))
         self._daemon_id: Optional[str] = None
         self._last_fired_date: Optional[datetime] = None
+        # dcy-020 / REQ-058 (BAT-028): asset-centric slot reconcile after each
+        # universe fetch (only when enabled = asset-centric mode).
+        self._slot_repo = slot_repo
+        self._instance_key = instance_key
+        self._reconcile_enabled = reconcile_enabled
+        self._trading_date_fn = trading_date_fn
+        self._last_universe_size: Optional[int] = None
 
     # ---- callable from a daemon thread loop --------------------------------
     def run_forever(self, stop: threading.Event, *, tick_sec: float = 60.0) -> None:
@@ -99,5 +110,36 @@ class SnapshotScheduler:
             reconcile_positions(store=self._store, broker=self._broker)
         except Exception:  # noqa: BLE001
             _log.exception("reconciliation pass failed")
+        if self._reconcile_enabled and self._slot_repo is not None:
+            try:
+                self._reconcile_slots(items)
+            except Exception:  # noqa: BLE001
+                _log.exception("slot reconcile pass failed")
         self._last_fired_date = self._clock()
         return True
+
+    # ---- asset-centric slot reconcile (dcy-020/REQ-058, BAT-028) ----------
+    def _reconcile_slots(self, items: list) -> None:
+        universe = {it.portfolio_id for it in items if getattr(it, "portfolio_id", None)}
+        if not universe:
+            _log.warning("slot reconcile skipped: empty universe (degrade guard)")
+            return
+        # mass-disappearance guard (D3): retire 보류 on N→0 (above) or >=50% shrink
+        allow_retire = True
+        prior = self._last_universe_size
+        if prior is not None and len(universe) < 0.5 * prior:
+            allow_retire = False
+            _log.warning(
+                "slot reconcile: universe shrank %d->%d (>=50%%) — retire held",
+                prior, len(universe),
+            )
+        if self._trading_date_fn is not None:
+            trading_date = self._trading_date_fn()
+        else:
+            trading_date = self._clock().date()
+        result = self._slot_repo.reconcile_universe(
+            self._instance_key, trading_date, universe, allow_retire=allow_retire,
+        )
+        self._last_universe_size = len(universe)
+        if any(result.values()):
+            _log.info("slot reconcile: %s (instance=%s)", result, self._instance_key)